Harmfulness of asbestos fiber has recently been pointed out, and asbestos-free gasketing profiles for use in, for example, joints of a converter housing and a transmission case of automobiles have been demanded. Gaskets for such uses are required to be thin, to exhibit excellent sealing properties, particularly oil sealing properties, with a low clamp pressure, and to have sufficient strength, particularly tensile strength, for withstanding repeated applications of a load such as a shear force.
With the latest marked advancement of techniques, there is an increasing demand for gaskets with sufficiently high performance for use under conditions getting more severe. However, it has been difficult to satisfy the above-described requirements, particularly strength requirements, without using asbestos fiber. For example, JP-A-62-164784 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses an asbestos-free composition for a joint sheet, but it turned out that the composition does not always meet the requirement of oil sealing properties with a low clamp pressure. Not arising when asbestos fiber is employed, this problem is inherent in the use of non-asbestos fibers.
On the other hand, various beater sheets using non-asbestos fibers have been proposed. Since non-asbestos fibers are generally less compatible with other compounding additives, such as rubbers, than asbestos fiber, beater sheets using them are not always satisfactory in oil sealing properties at a low clamp pressure. This problem has become acute with the recent tendency that the conditions of use of beater sheets are getting more severe.